Conventionally, resin materials such as polycarbonate, polyacrylate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyolefin, and ABS are excellent in transparency and have a smaller weight than inorganic glass, so that these, as organic glass, are used as a substitute for inorganic glass in various fields. In particular, among these kinds of organic glass, polycarbonate is excellent in shock resistance, heat resistance, transparency, and the like, and is studied as organic glass that is used as an exterior member of a window or the like of an automobile.
On the other hand, as compared with inorganic glass, organic glass is inferior in terms of weather resistance and abrasion resistance, so that, in order to compensate for these drawbacks, lamination of a surface protective layer formed of a cured resin on the surface of organic glass is generally carried out. However, there are numerous demands for improvement of desired performance of the organic glass, so that mere lamination of a surface protective layer formed of a cured resin cannot follow or meet these demands. In particular, when organic glass is used as an exterior member, the organic glass is used in an environment in which the organic glass is exposed to wind, rainfall, and ultraviolet rays and is liable to undergo scratches, so that it is demanded to improve the weather resistance and abrasion resistance. Above all, with respect to organic glass for exterior member that is used in the field of automobiles, it is demanded to provide the organic glass with a further more excellent weather resistance and abrasion resistance from the viewpoint of safety, visibility and the like.
Therefore, it is proposed to improve the abrasion resistance and weather resistance of the organic glass by forming a cured layer of a curable resin and an inorganic oxide film such as silicon dioxide on the surface of the organic glass to form an organic glass laminate. For example, Patent Document 1 discloses an organic glass laminate in which a cured film is formed on the surface of a transparent or semitransparent plastic substrate by the wet method, and a plasma CVD layer is formed on the cured film under specific conditions. Further, Patent Document 2 discloses an organic glass laminate in which a first weather-resistant layer of polyurethane or polyurethane acrylate is formed on a plastic base material, and further a first abrasion-resistant layer of an inorganic substance such as silicon dioxide is formed on the first weather-resistant layer. In Patent Documents 1 and 2, it is assumed that the thickness of the inorganic oxide film is preferably 0.5 μm or more in view of providing the abrasion resistance. However, an inorganic oxide film having such a thickness requires a large amount of time for forming and moreover has a poor processability, so that cracks are liable to be generated when the inorganic oxide film is bent. Therefore, the inorganic oxide film must be formed directly on a molded organic glass, thereby disadvantageously leading to a complicated and cumbersome production process.
Furthermore, in a conventional organic glass laminate in which a cured layer and an inorganic oxide film are laminated, the inorganic oxide film may sometimes be delaminated by generation of cracks, so that the conventional organic glass laminate still has not been fully satisfactory in view of the weather resistance as well.
In view of the presence of such a conventional art as a background, it is eagerly demanded in an organic glass laminate used as an exterior member that a new technique capable of providing excellent weather resistance and abrasion resistance is developed.